Climate Climate & Energy

What do the climate scientists think?

No Se Nada had an interesting post last week claiming climate scientists are starting to worry that they've oversold climate change:

What I see is something that I am having a hard time labeling, but that I might call either a "hangover" or a "sophomore slump" or "buyers remorse." None fit perfectly, but perhaps the combination does. I speak for (my interpretation) of the collective: {We tried for years - decades - to get them to listen to us about climate change. To do that we had to ramp up our rhetoric. We had to figure out ways to tone down our natural skepticism (we are scientists, after all) in order to put on a united face. We knew it would mean pushing the science harder than it should be. We knew it would mean allowing the boundary-pushers on the "it's happening" side free reign while stifling the boundary-pushers on the other side. But knowing the science, we knew the stakes to humanity were high and that the opposition to the truth would be fierce, so we knew we had to dig in. But now they are listening. Now they do believe us. Now they say they're ready to take action. And now we're wondering if we didn't create a monster. We're wondering if they realize how uncertain our projections of future climate are. We wonder if we've oversold the science. We're wondering what happened to our community, that individuals caveat even the most minor questionings of barely-proven climate change evidence, lest they be tagged as "skeptics." We're wondering if we've let our alarm at the problem trickle to the public sphere, missing all the caveats in translation that we have internalized. And we're wondering if we've let some of our scientists take the science too far, promise too much knowledge, and promote more certainty in ourselves than is warranted.}

I was also at the AGU meeting, and here's my take:

There is no proof in science, but there are mountains of evidence

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Correlation is not proof of causation. There is no proof that CO2 is the cause of current warming.

Answer: There is no "proof" in science -- that is a property of mathematics. In science, what matters is the balance of evidence, and theories that can explain that evidence. Where possible, scientists make predictions and design experiments to confirm, modify, or contradict their theories, and must modify these theories as new information comes in.

Water vapor is indeed a powerful greenhouse gas, but there is plenty of room for CO2 to play a role

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: H2O accounts for 95% of the greenhouse effect; CO2 is insignificant.

Answer: According to the scientific literature and climate experts, CO2 contributes anywhere from 9% to 30% to the overall greenhouse effect. The 95% number does not appear to come from any scientific source, though it gets tossed around a lot.

Warning: techno-engineering speak ahead

Amory Lovins is rightfully admired by environmentalists. But nobody is right all the time, and the hydrogen path is one of his few mistakes. He summarizes his argument for hydrogen in Twenty Hydrogen Myths (PDF). More extensive discussion is embedded in his book Winning the Oil Endgame (book-length PDF).

His basic proposal:

‘Climate scientists dodge the subject of water vapor’–No, they really don’t

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Climate scientists never talk about water vapor -- the strongest greenhouse gas -- because it undermines their CO2 theory.

Answer: Not a single climate model or climate textbook fails to discuss the role water vapor plays in the greenhouse effect. It is the strongest greenhouse gas, contributing 36% to 66% to the overall effect for vapor alone, 66% to 85% when you include clouds. It is however, not considered a climate "forcing," because the amount of H2O in the air basically varies as a function of temperature.

‘We are just recovering from the LIA’–Why should we expect this to happen?

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Today's warming is just a recovery from the Little Ice Age.

Answer: This argument relies on an implicit assumption that there is a particular climatic baseline to which the earth inexorably returns -- and thus that a period of globally lower temperatures will inevitably be followed by a rise in temperatures. What is the scientific basis for that assumption?

‘The CO2 rise is natural’–No skeptical argument has been more definitively disproven

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: It's clear from ice cores and other geological history that CO2 fluctuates naturally. It is bogus to assume today's rise is caused by humans.

Answer: We emit billions of tons of CO2 into the air and, lo and behold, there is more CO2 in the air. Surely it is not so difficult to believe that the CO2 rise is our fault. But if simple common sense is not enough, there is more to the case. (It is worth noting that investigation of this issue by the climate science community is a good indication that they are not taking things for granted or making any assumptions -- not even the reasonable ones!)

Navajo protest third coal-fired plant on reservation land

Members of the Navajo Nation and their supporters have been blockading the site of a proposed coal-fired power plant in northwestern New Mexico for more than a week now, hoping to halt construction of what they believe will be a social and ecological disaster.

If completed, the Desert Rock Power Plant will cover 600 acres in the largest American Indian reservation in the nation, and it will be the third coal-fired plant on Navajo land.

Let’s not fetishize size

Many environmentalists are reverse size queens -- "small is beautiful."

When Schumacher wrote the book of that title, he was responding to a real tendency to ignore diseconomies of scale -- a tendency that still exists. Up to a certain point, both organizations and physical plants produce more output for each unit of input as they grown in size. Past that point, costs of gigantism kick in, and efficiency begins to fall instead of rising.

But Schumacher assumed that this point always occurs at small or medium sizes. In fact, there are many cases in which you get economies of scale up to very large sizes indeed.

For example, computer CPUs are still made in giant factories, not neighborhood plants; your computer would cost a whole lot more if that were not the case.

‘Natural emissions dwarf human emissions’–But emissions are only one side of the equation

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: According to the IPCC, 150 billion tonnes of carbon go into the atmosphere from natural processes every year. This is almost 30 times the amount of carbon humans emit. What difference can we make?

Answer: It's true that natural fluxes in the carbon cycle are much larger than anthropogenic emissions. But for roughly the last 10,000 years, until the industrial revolution, every gigatonne of carbon going into the atmosphere was balanced by one coming out.

What humans have done is alter one side of this cycle. We put approximately 6 gigatonnes of carbon into the air but, unlike nature, we are not taking any out.